(define (collect-randoms number-randoms)
  (if (= 0 number-randoms)
    nil
    (cons (random 1.0) 
          (collect-randoms (- number-randoms 1)))))

(define (linear)
  (let ((first-random (random 1.0))
        (second-random (random 1.0)))
    (if (< first-random second-random)
      first-random
      second-random)))

(define (triangular)
  (let ((first-random (random 1.0))
        (second-random (random 1.0)))
    (* 0.5 (+ first-random second-random))))

(define pitch-gamut (list 0 3 6 8))
(define register-gamut (list 60 84 96 108))
(define onset-gamut (list 0.77 1.34 3.17 5.17 9.12))
(define duration-gamut (list 0.35 0.89 2.3 3.4))
(define amplitude-gamut (list 0.2 0.3 0.35))

(define (choose-from-gamut gamut)
  (nth (random (length gamut)) gamut))

(define (generate-chord number-pitches pitches registers start dur amp)
  (if (<= number-pitches 0)
    nil
    (cons (new midi 
            :time start
            :keynum (+ (choose-from-gamut pitches)
                       (choose-from-gamut registers))
            :amplitude amp
            :duration dur)
          (generate-chord (- number-pitches 1) 
                          pitches registers start dur amp))))

(define (gamut-chords number-chords pitches registers onsets 
                      durations amplitudes start-time)
  (let* ((onset-time (choose-from-gamut onsets))
         (next-onset (+ start-time onset-time)))
    (if (<= number-chords 0)
      nil
      (append (generate-chord 3 pitches registers onset-time
                              (choose-from-gamut durations)
                              (choose-from-gamut amplitudes))
              (gamut-chords (- number-chords 1) pitches registers onsets
                            durations amplitudes next-onset)))))

(events (append (gamut-chords 20 pitch-gamut register-gamut onset-gamut
                              duration-gamut amplitude-gamut 0.0)
                (gamut-chords 20 pitch-gamut register-gamut onset-gamut
                              duration-gamut amplitude-gamut 0.0)
                (gamut-chords 20 pitch-gamut register-gamut onset-gamut
                              duration-gamut amplitude-gamut 0.0))
        "test.mid")